WO2020244984A1

WO2020244984A1 - Method for producing a near-net-shape fiber body, fiber body, method for producing a ceramic component, and ceramic component

Info

Publication number: WO2020244984A1
Application number: PCT/EP2020/064668
Authority: WO
Inventors: Fiona KESSEL; Linda KLOPSCH; Martin Friess; Charlotte ZÖLLNER; Volker Jehle; Nancy-Jane BILLER
Original assignee: Deutsches Zentrum für Luft- und Raumfahrt e.V.
Priority date: 2019-06-04
Filing date: 2020-05-27
Publication date: 2020-12-10
Also published as: DE102019115039A1; EP3980388A1

Abstract

The invention relates to a method for producing a near-net-shape fiber body (100), comprising the steps: dispersing a fiber material (102) in a noncompressible fluid (106), thereby forming a fiber dispersion (108), and conveying the fiber dispersion (108) through a sieve mold (110) with a selected geometrical design, wherein the noncompressible fluid (106) is conveyed through one or more passage-openings (112) of the sieve mold (110), and fibers of the fiber material (102) are deposited on or in the sieve mold (110) and form a fiber body, the geometrical design of which is predefined by the geometrical design of the sieve mold (110).

Description

Process for the production of a near net shape fiber body, fiber body, process for the production of a ceramic component and ceramic component

The present invention relates to a method for producing a near-end-contour fiber body.

The present invention also relates to a fiber body produced by a method according to the invention.

The present invention further relates to a method for producing a ceramic component and a ceramic component produced according to the aforementioned method.

From DE 38 40 781 A1 a fiber composite ceramic and a method for its production is known, the method consists in impregnating fibers with a molten polysilazane in a first step and converting the polysilazane in the fibers into the infusible state in a second step and in a third step the impregnated fibers are heated to 800 ° C. to 2,000 ° C. in a nitrogen, noble gas or ammonia atmosphere.

US 2004/0005462 A1 discloses a sliding material consisting of a carbon fiber-reinforced carbon composite material comprising fine particles of a simple substance from a group IV to group VI element or a carbide, a nitride or an oxide thereof.

From EP 0 555 130 B1 a method for producing a part from composite material with a ceramic matrix is known. The method comprises the production of a fibrous preform, the impregnation of the preform by means of an impregnation composition which contains an organosilicon polymer as ceramic precursor, and the implementation of a thermal treatment, at the end of which the precursor is passed through without a fusible phase. run, is converted into ceramic. The method further comprises that a reinforcement of the preform is carried out by impregnation by means of an impregnation composition which contains a mixture of a thermosetting monomer and the ceramic precursor polymer, and by thermal treatment, in the course of which the crosslinking of the monomer is first realized in such a way that that prior to the conversion of the precursor into ceramic in the entire volume of the preform an in situ crosslinking of the polymeric mixture is obtained, and then a densification of the reinforced preform by a ceramic matrix is carried out.

DE 10 2013 216 437 A1 describes the use of ceramic materials in machine components of a paper machine as components for

Known wear surfaces, the ceramic materials are formed as a fiber-ceramic composite, which fibers and a ceramic matrix comprise.

WO 2011/007184 A2 discloses a method for producing a

A fiber matrix, the method comprising providing a starting material which comprises a liquid carrier, fibers and a binder, passing the starting material over a substrate to deposit fibers on the substrate, forming a 3-dimensional fiber matrix and curing the binder .

From WO 2019/228683 A1 a continuous composite structure, a burner surface, a burner assembly, a method for producing a burner surface, the use of the burner surface and the use of the burner assembly is known.

A ceramic fiber composite structure is known from US 2004/0132607 A1, which is joined by means of an at least partially ceramic binder, the at least partially ceramic binder being formed by a nanoclay and at least one ceramic precursor material or a ceramic material. US 2017/0341004 A1 discloses a candle filter comprising a hollow cylindrical tube, high-temperature-stable fibers, at least one binding agent and optionally another binding agent. The at least one binding agent and optionally the further binding agent are distributed essentially homogeneously in a wall of the candle filter.

EP 2 046 700 B1 discloses a method for producing a composite structure or a section of a composite structure of a brake band of a brake disc, comprising the production of a composite ceramic structure comprising carbon fibers, silicon and silicon carbides, whereby a body of a brake band is obtained which has at least one braking surface comprises, machining the braking surface, wherein a layer of the surface is removed such that carbon that is not bonded with silicon is present on the surface, an at least partial removal of the carbon that is not bonded with silicon from the surface and the

Applying a protective coating to the braking surface, the step of removing the carbon that is not bonded with silicon being carried out by cleaning the braking surfaces with an abrasive jet or by burning off the braking surfaces.

A carbide ceramic material is known from DE 10 2011 001 065 A1 which is produced by infiltration of a porous carbon containing the preform and a mass fraction of free carbon less than 1% and a mass fraction of free carbide former less than 1%.

The present invention is based on the object of providing a method by means of which a near-net-shape fiber body can be produced in one step and as simply as possible.

The aforementioned object is achieved by a method according to claim 1. The shape of the sieve is selected in particular depending on the application depending on the shape of the near-net-shape fiber body.

The fiber dispersion is preferably conveyed along at least one conveying direction, the at least one conveying direction being arranged transversely to an envelope of the sieve shape.

The envelope is in particular an envelope surface, which is also referred to in mathematics as an envelope curve.

The geometric shape of the fiber body made of deposited fibers is - as mentioned - predetermined by the geometric shape of the sieve shape and corresponds in particular to the geometric shape of the sieve shape essentially.

In particular, because the geometric shape of the sieve shape can be curved or can have any other shape from which the fiber body can be demolded, 3-dimensional fiber bodies in particular can be produced in one step. A joining of several fiber body parts, as is customary, is therefore unnecessary.

The inventive method, for example, hollow bodies can be produced, which many conventional methods, such as hot pressing methods, are inaccessible.

The method according to the invention forms in particular an application of a wet web method for three-dimensional fiber bodies.

The fibers in one area of the resulting near-net-shape fiber body enclose in particular an angle of approximately 0 ° to approximately 90 ° with fibers in another area of the near-net-shape fiber body. Even comparatively steep angles within fiber bodies can be represented in particular with the method according to the invention. With the hot pressing process, only limited 3-dimensional bodies can be produced.

In the method according to the invention, material and thus costs can be saved compared to hot pressing methods.

As a result of the promotion, the deposited fibers in particular essentially have an orientation which is parallel to an envelope of the screen.

The sieve shape is preferably reusable. In this way, costs can be saved compared to methods with single-use negative molds.

During the dispersion, the fibers are preferably separated. It can be provided here that the fibers are present in the form of fiber filaments or are retained as fiber bundles, so-called rovings.

In the context of the invention, the sieve shape is a shape which partially or completely has a mesh and / or grid-like structure.

For stability of the sieve shape, it can be advantageous if the sieve shape comprises a supporting core and a sieve grid.

The passage openings preferably have a diameter which is smaller than the length of the fibers used.

It can be favorable if the fiber dispersion is conveyed by means of a conveying device.

In particular, a flow of the fiber dispersion is generated from a deposition side of the sieve mold, on which the fibers are deposited, to a suction side of the sieve mold. In particular, essentially no or only a few fibers are deposited on the suction side.

In particular, the fiber dispersion is sucked off in the direction of an inside of the sieve mold, the fiber body being formed on an outside of the sieve mold.

Alternatively, it can be provided that the fiber dispersion is sucked in from an outside of the sieve mold, whereupon the fiber body is formed on an inside of the sieve mold.

It can be favorable if the delivery device is a pump device which comprises one or more pumps and / or one or more flow deflection elements.

As an alternative to a pump device, the conveyance can also be designed by gravity conveyance.

Flow deflection elements can for example be designed in the form of line sections of a line device. The line device is preferably part of the pump device.

The one or more pumps are, for example, vacuum pumps.

The one or more pumps preferably generate a laminar flow of the fiber dispersion in the direction of the surface of the sieve mold.

Alternatively, the method can also be carried out with turbulent flow. Preferably, the sieve shape is held immobile Lich during deposition relative to a wall of a container in which the fiber dispersion is received. The sieve shape is in particular firmly positioned.

Alternatively, it can be provided that the sieve shape is moved, in particular evenly, through the container. For example, a Rotationsbe movement of the sieve shape, in particular about its axis of symmetry, can be provided.

It can be provided that the sieve shape with the near-net-shape fiber body created therein is removed while the conveyance of the fiber dispersion is maintained. This can prevent deposited fibers from being swirled around by the flow inside the container.

Alternatively, it can be provided that the conveyance of the fiber dispersion is stopped before the near-net-shape fiber body is removed and that the incompressible fluid and / or dispersant and / or binder is removed under negative pressure. In particular, the sieve mold runs "dry" and only then is the near-net-shape fiber body removed.

After removal of the sieve mold with the near-net shape fiber body created therein or on it, the fiber body is preferably dried together with the sieve mold, in particular in a drying oven, before it is removed from the sieve mold.

The fiber dispersion preferably comprises a dispersant and / or a binder. In particular, a dispersant and / or a binder is admixed with the fiber dispersion.

According to a preferred embodiment, the dispersant corresponds to the binder. Preferred binders and / or dispersants are carboxymethyl cellulose (CMC) and xanthan. In addition or as an alternative, further

conventionally used binders and / or dispersants can be used.

It can be provided that the dispersant is added to the incompressible fluid before the dispersing of the fiber material.

Additionally or alternatively, it can be provided that the binder is added to the fiber dispersion, in particular in order to adjust a viscosity and / or to increase the shear forces of the incompressible fluid.

The fibers of the fiber dispersion are preferably kept in suspension and / or sedimentation is avoided and / or made more difficult by the dispersant.

It can be provided that the binding agent is an adhesive which further solidifies the resulting near net shape fiber body.

The fiber dispersion preferably has a fiber concentration of approximately 0.1 g / l to approximately 10 g / l, in particular from approximately 1 g / l to approximately 5 g / l.

The incompressible fluid is preferably water or an alcohol or a mixture thereof.

It can be provided that incompressible fluid contains poly tungstate.

Preferred alcohols are ethanol and / or isopropanol.

It can be favorable if the fibers of the fiber material consist of one

ceramic material. Alternatively - depending on the application - fibers from other fibers are also available

Materials suitable.

Preferably, some or all of the fibers of the fiber material are made from one or more of the following materials: oxide ceramic materials, carbon, silicon carbide, aramid, glass.

An oxide ceramic material is, for example, aluminum oxide.

In the case of glass fibers, for example, it can be provided that a surface charge of the fibers is influenced by means of the binding agent and / or the selection of the incompressible fluid.

The surface charge of the fibers is preferably influenced in such a way that they repel one another. In this way an agglomeration of fibers can be avoided.

It can be provided that an electric field is applied to the fiber dispersion, and thus - depending on the fiber material - an orientation of the fibers is established.

In particular, fiber bodies with different fibers can be produced by producing a fiber dispersion which contains different fibers.

It can be provided that a graduation of fibers is introduced into the near net shape fiber body.

It can be favorable if the fiber material comprises recycled fibers or is formed from them. This enables value-added processing, for example of recycled glass fibers or recycled carbon fibers. The fiber material preferably comprises short fibers or is formed from short fibers. In particular, the fiber material comprises fibers with an average length of approximately 2 mm to approximately 40 mm or is essentially formed from fibers with an average length of approximately 2 mm to approximately 40 mm.

The mean length is defined in particular as the arithmetic mean of the lengths.

An orientation of the fibers in the near-net shape fiber body is preferably predetermined by an envelope of the sieve shape, the fibers in particular being oriented essentially along an area which is arranged parallel to the envelope of the sieve shape.

The envelope of the screen shape is preferably mapped by deposited fibers, curvatures in particular, as well as areas of the envelopes that are just formed, are mapped by deposited fibers.

The envelope of the sieve shape is preferably an envelope of a

Outside of the sieve mold and / or an envelope of an inside of the sieve mold.

The envelope is in particular a geometric surface of the screen shape.

The near-net shape fiber body preferably has a fiber content in the Z direction of at most approximately 7% by volume, in particular of at most approximately 3% by volume, for example of approximately 1% by volume, the Z direction in each case being transverse to a surface is arranged, along which the fibers in the near-net-shape fiber body are essentially oriented. Fibers in the Z direction lead to restoring forces, for example when the fiber body is pressed. Due to the reduced restoring forces, a tendency to delamination in the near net shape fiber body can be reduced.

The respective Z direction is preferably arranged at a point on the surface of the fiber body, in particular perpendicular to the corresponding tangential plane.

Preferably, the fiber body is substantially obtained with a

Formed fiber bundle structure. For example, a fiber resolution is low.

The fiber bundle structure preferably remains in the fiber dispersion

Essentially preserved. In particular, with 80% of the fiber material or more, for example 90% or more, the fiber bundle structure is retained.

Preferably less than 20%, in particular less than 10%, of the fiber bundles dissolve.

A "fiber dissolution" is to be understood in particular as a separation of individual components of a fiber bundle.

For example, the proportion of carbon and carbide in a ceramic component produced on the basis of the corresponding near-net shape fiber body can be controlled via the degree of fiber dissolution. A strong dissolution of a fiber bundle structure into single filaments leads to a high carbide content in the ceramic component. A low resolution of the fiber bundle structure leads to a high proportion of carbon in the component, this carbon proportion being composed of carbon in carbon fibers and of carbon in an amorphous carbon matrix. In order to keep the fiber bundle resolution low, for example, it can be provided that longer fibers, in particular in the range between 15 mm and 40 mm, are used. For improved deposition of the fibers, it can be advantageous if one or more longitudinal center axes of the one or more passage openings of the sieve mold is arranged transversely with respect to radial directions of the longitudinal center axis of the sieve mold.

In this way it can be avoided that fibers aligned parallel to the flow direction pass through the passage openings.

The sieve shape is preferably subjected to negative pressure by means of a conveying device in a container in which the fiber dispersion is received. In particular, by means of a conduit device, incompressible fluid is diverted from the container through a fluid outlet and the incompressible fluid is reintroduced into the container by means of a conveying device through a fluid inlet.

In particular, suction is generated within the sieve shape.

The invention further relates to a fiber body, in particular a near-net-shape fiber body which is Herge according to a method according to the invention.

The fiber body is preferably a component, in particular a CFRP component.

One area of application for the component mentioned is, for example, the automotive industry and the fiber-reinforced components used there.

The fiber body according to the invention preferably has one or more of the features described in connection with the method according to the invention and / or one or more of the advantages described in connection with the method according to the invention. The fiber body according to the invention is particularly suitable for use as a green body in a ceramization method described below.

The invention also relates to a method for producing a ceramic component, comprising:

Production of a near net shape fiber body according to a

method according to the invention;

Carrying out pyrolysis on the near-net-shape fiber body, an open-pored carbon body being produced; and

Carrying out a ceramization on the resulting open-pore carbon material body.

The ceramization is expediently carried out by infiltrating the open-pore carbon body with liquid carbide former, the carbide former being in particular silicon.

The liquid silicon reacts with carbon in the open-pore carbon body and forms silicon carbide. The open porosity of the carbon body enables the carbon to be infiltrated with carbide formers.

The fiber structure is essentially retained. This is in particular a difference to components manufactured by means of fiber injection, in which the fibers generally react completely to form silicon carbide during the infiltration with silicon.

As an alternative to infiltration with a carbide former, in particular a liquid, provision can be made for a polymer infiltration and pyrolysis process to be carried out for ceramization.

For this purpose it can be provided that the ceramization is carried out by infiltrating the open-pore carbon body with a polymer material, in particular an organometallic or organosilicon polymer material, and subsequent pyrolysis is carried out.

According to the invention, a ceramic component is provided which is produced according to the method according to the invention.

A fiber content of the ceramic component is preferably approximately 50% by volume or less, in particular approximately 25% by volume to approximately 35% by volume, based on a total volume of the ceramic component.

Due to the comparatively high fiber content, the respective

ceramic components preferably have an improved damage tolerance.

The fibers can fulfill a support function.

The ceramic component is preferably a CMC (Ceramic Matrix Composites) component.

The ceramic component is used, for example, in lines for corrosive

Use of hot gases.

Further preferred features and advantages of the invention are the subject of the following description and the drawing of FIG

Embodiments.

Show it :

Figure 1 is a schematic representation of an embodiment of a

Method according to the invention for producing a near-net-shape fiber body;

FIG. 2 shows a schematic illustration of a further embodiment of a method according to the invention for producing a near-net-shape fiber body; FIG. 3 shows a schematic side view of a core of a sieve mold which is suitable for use in the method according to FIG. 1 or according to FIG. 2;

FIG. 4 shows a schematic cross-sectional view of the core of the sieve mold from FIG. 3 through the plane designated by IV in FIG. 3;

FIG. 5 shows a section of a computer tomography recording of a

Near net shape fiber body which was produced with a method according to the invention, wherein the fiber body has a substantially hollow cylindrical shape; and

FIG. 6 shows a schematic representation of a sequence of an embodiment of a method for ceramization in which a near-net-shape fiber body serves as the green body.

Identical or functionally equivalent elements are denoted by the same reference symbols in all figures.

A first embodiment of a method for producing a near-net-shape fiber body 100 is shown schematically in FIG. A pump circuit can be seen, by means of which a flow guide can be generated so that fibers are deposited on an outside of a sieve mold 110 to form a near-net-shape fiber body 100.

A near-net-shape fiber body 100 produced in this way is shown by way of example in FIG.

According to the first embodiment of the method, a fiber material 102 is dispersed in a container 104 in an incompressible fluid 106, a fiber dispersion 108 being formed. Individual fibers of the fiber material 102 are in the present case indicated schematically in an already dispersed form in the fiber dispersion 108 by lines.

The fibers of the fiber material 102 are preferably made of a ceramic material.

Fibers made from one of the following materials are particularly suitable as fiber material 102: oxidic ceramic material, in particular aluminum oxide, carbon, silicon carbide, aramid, glass.

It can be advantageous if a fiber material 102 is used which comprises a mixture of the fibers mentioned.

In the present case, glass fibers and aluminum oxide fibers with an average length in a range from approximately 6 mm to approximately 25 mm are used.

In the present case, water is used as the incompressible fluid 106.

Depending on the fiber selection, however, it can be advantageous if an alcohol, for example ethanol or isopropanol, or a mixture of alcohol and water is used as the incompressible fluid.

In particular, when fibers made of aluminum oxide are used, the use of poly tungstate as a component of the incompressible fluid 106 can be advantageous. The use of poly tungstate in the incompressible fluid 106 can also be advantageous for other fiber materials 102.

Depending on the selection of the fiber material 102 and the incompressible fluid, it can be advantageous if an orientation of the fibers is accelerated and / or reinforced by applying an electric field.

In the present case, the container 104 is a vat. The fiber dispersion 108 in the present case also comprises carboxymethyl cellulose (CMC), which acts as a binder and increases a viscosity of the fiber dispersion 108 so that it can be processed better. In the present case, the binder also serves as a dispersant to assist in dispersing the fiber material 102.

As an alternative or in addition to CMC, xanthan gum or another binding agent and / or dispersant can also be used.

In the present case, the binder also serves as an adhesive for consolidating the structure of the resulting near-net-shape fiber body 100.

A fiber concentration in the fiber dispersion 108 is in the present case approximately 0.1 g / l fiber dispersion to approximately 10 g / l fiber dispersion, in particular approximately 1 g / l fiber dispersion to approximately 5 g / l fiber dispersion.

The sieve mold 110 is arranged within the container 104. In the present case, the sieve mold 110 serves as a positive mold for the near-net-shape fiber body 100 resulting from the method.

The sieve mold 110 comprises through openings 112 distributed homogeneously over the sieve mold 110, which connect a suction side 114 and an attachment side 116 of the sieve mold to one another in a fluid-effective manner. In FIGS. 1 and 2, the passage openings 112 are indicated by a grid pattern.

In the present case, the suction side 114 is formed by an inside of a lateral surface of a sieve shape 110 which is essentially hollow-cylindrical. The deposit side 116 is formed by an outside of the jacket surface of the sieve mold 110 (compare FIGS. 3 and 4).

A line device 118 is arranged on the suction side 114 of the sieve mold 110. The line device 118 serves to line the incompressible fluid 106 and in the present case comprises a plurality of line sections 120 which adjoin one another.

A discharge line section 120a in the present case forms a fluid outlet 121, through which incompressible fluid 106 is discharged from the container 104.

In the present case, a supply line section 120b forms a fluid inlet 123 through which incompressible fluid 106 is supplied to the container 104 again.

The discharge line section 120a and the supply line section 120b are connected to one another by means of further line sections 120 via a pump 122.

The pump 122 is used to convey incompressible fluid 106 and to generate a flow from the deposit side 116 to the suction side 114.

The line device 118 and the pump 122 each form components of a delivery device 124, which in the present case is designed as a pump device 126.

A flow from the fluid outlet 121 to the fluid inlet 123 is generated by means of the pump 122.

The flow of the incompressible fluid 106 from the fluid outlet 121 to the fluid inlet 123 is indicated by arrows.

A flow of the fiber dispersion 108 arises from the deposition side 116 to the suction side 114. The fibers of the fiber dispersion 108 are deposited on the deposit side 116, while the incompressible fluid 106 flows through the passage openings 112 and is conveyed through the line sections 120 of the line device 118 by means of the pump 122.

The flow within the container 104 is maintained until enough fibers have deposited so that a near-net-shape fiber body 100 with sufficient thickness has arisen.

The fibers are predominantly oriented along a surface which is arranged parallel to an envelope of the sieve shape 110.

The fiber body 100 also has curved areas if the envelope of the screen shape 110 has curved areas. The curved regions of the sieve shape are mapped in one piece in the near net shape fiber body 100.

While the flow continues, the screen form 110 is removed together with the fiber body 100 and then dried in a drying oven at about 80 ° C. for at least 2 hours. Alternatively, other drying methods can also be used.

After the near net shape fiber body 100 has dried, it is demolded.

A degree of fiber resolution is preferably low, so that a bundle structure of the fibers of the fiber material 102 is essentially retained.

In particular, the fiber bundle structure is retained in 80% of the fibers of the fiber material 102 or more, for example 90% or more.

Preferably less than 20%, in particular less than 10%, of the fiber bundles dissolve. A fiber body 100 has been created, the shape of which essentially corresponds to the shape of the screen shape 110. By choosing different

Sieve shapes can therefore be produced with differently shaped fiber bodies 100.

As is shown schematically in FIG. 6, the fiber body 100

then subjected to ceramization.

However, even without ceramization, the fiber body 100 has sufficient stability to be used without ceramization and represents a component without further processing. For example, the fiber body 100 can be used in the automotive industry.

Alternatively, the fiber body 100 can also be used in the textile industry. The fiber body 100 can, for example, form part of a cup of a brassiere.

In a method for ceramization, the near-net shape fiber body 100 represents in particular a green body.

For the ceramization described below, the fiber body 100 is first pyrolyzed at temperatures of 1,000 ° C. to 1,600 ° C., as a result of which an open-pore carbon body 140 is produced.

The pyrolysis is preferably carried out with the exclusion of oxygen, so that oxidation can be avoided or minimized.

The open-pore carbon body 140 is then with a

Carbide former, in this case silicon (Si), infiltrated, with the silicon in liquid form passing through the pores of the open-pored carbon body 140 into its interior and reacting there with carbon to form silicon carbide. The reaction with silicon to form silicon carbide produces a ceramic component 150.

As an alternative to the so-called LSI (liquid silicon infiltration) process described above, ceramization of the near-net-shape

Fiber body 100 can also be carried out by means of a PIP (polymer infiltration and pyrolysis) method.

For this purpose, the open-pore carbon body 140 is preferably infiltrated, often in several steps, with a polymer material, for example an organometallic or an organosilicon material.

The infiltrated open-pore carbon body 140 is then pyrolyzed, for example in a solid-phase thermolysis.

A fiber content of the ceramic component 150 is in a range from approximately 25% by volume to approximately 35% by volume based on a total volume of the

ceramic component 150.

The ceramic component 150 is particularly suitable for use in guide tubes for corrosive hot gases.

The second embodiment of a method for producing a near net shape fiber body 100 shown in FIG. 2 differs essentially from the first embodiment shown in FIG. 1 in that the sieve mold 110 is arranged in a lower region - near a bottom wall - of the container 104 and that a flow direction runs opposite to the flow direction according to the first embodiment.

The discharge line section 120a is arranged on the bottom wall 142 of the container 104. The supply line section 120b is in one with respect to FIG The upper region of the container 104 is arranged in the direction of gravity and protrudes into the fiber dispersion 108.

Otherwise, the second embodiment of a method shown in FIG. 2 corresponds to the first embodiment shown in FIG. 1, so that reference is made to the description thereof.

The ceramization is preferably carried out as described above.

As an alternative to the illustrated embodiments, it can also be provided that the suction side 114 is formed by an outer surface of the sieve mold 110 and the deposition side 116 is arranged in an interior space and / or on an inside of the sieve mold 110. In this case, a flow is generated from the interior and / or the inside to the surroundings of the sieve mold 110 and the fibers are deposited on an inside of the sieve mold 110.

As can be seen in particular in FIGS. 3 and 4, the screen shape 110 preferably has an at least approximately hollow cylindrical shape

Base body, which is pierced by regularly arranged through openings 112.

A supporting core of a sieve mold 110 is shown in FIGS. 3 and 4, which core increases the stability of the sieve mold 110.

Before use, a mesh screen, preferably made of metal, for example metal gauze, is placed over the supporting core.

An envelope of the screen shape 110 is in the present case at least approximately in the form of a hollow cylinder.

In the present case, a connecting section 144 adjoins the at least approximately hollow cylinder-shaped base body, which in FIG assembled state is connected to line sections 120 of the line device 118. The flow is guided from the sieve mold 110 into the conduit device 118 through the connecting section 144.

As can be seen in particular in FIG. 4, the passage openings are arranged with main directions of extent transversely with respect to radial directions of a longitudinal central axis 145 of the sieve mold 110.

In this way it can be avoided that fibers which are aligned in the flow direction pass through the passage openings 112.

FIG. 5 shows a section of a computer tomography recording of a near-net-shape fiber body 100 after consolidation. It can be seen from the picture that the fibers are retained as fiber bundles - so-called rovings - and that there is little fiber in the Z-direction.

The Z-direction is the respective direction which is arranged transversely to the surface along which the fibers are oriented. As already mentioned, this surface is parallel to the envelope of the screen shape 110.

List of reference symbols near net shape fiber bodies

Fiber material

container

incompressible fluid

Fiber dispersion

Sieve shape

Passage opening

Suction side

Deposit side

Conduction device

Line section

a discharge line section

b feed line section

Fluid outlet

pump

Fluid inlet

Conveyor

Pump device

open-pore carbon body

Bottom wall

Connection section

Longitudinal central axis

ceramic component

Claims

1. A method for producing a near-net-shape fiber body (100), the method comprising:

Dispersing a fiber material (102) in an incompressible fluid (106) to form a fiber dispersion (108); and conveying the fiber dispersion (108) through a sieve mold (110) with a selected geometric shape, wherein the incompressible fluid (106) is conveyed through one or more passage openings (112) of the sieve mold (110) and wherein fibers of the fiber material are conveyed (102) at or in the

Deposit the sieve shape (110) and form a fiber body, the geometric shape of which is predetermined by the geometric shape of the sieve shape (110).

2. The method according to claim 1, characterized in that a

Flow of the fiber dispersion (108) from a deposition side of the sieve form (110) on which the fibers are deposited to a

The suction side (114) of the sieve mold (110) is generated.

3. The method according to claim 1 or 2, characterized in that the fiber dispersion (108) is conveyed by means of a conveying device (124) along at least one conveying direction, wherein the conveying device (124) is a pump device (126), which one or several pumps and / or one or more

Includes flow deflection elements.

4. The method according to any one of the preceding claims, characterized in that the sieve mold (110) with the end-contour fiber body (100) created therein is removed from the fiber dispersion (108) while maintaining the conveyance of the fiber dispersion (108) .

5. The method according to any one of the preceding claims, characterized in that the fiber dispersion (108) comprises a dispersant and / or a binder and / or that the fiber dispersion (108) is admixed with a dispersant and / or a binder.

6. The method according to any one of the preceding claims, characterized in that the fiber dispersion (108) has a fiber concentration of about 0.1 g / l to about 10 g / l, in particular from about 1 g / l to about 5 g / l.

7. The method according to any one of the preceding claims, characterized in that the incompressible fluid (106) is water or an alcohol or a mixture thereof, the incompressible fluid (106) in particular containing poly tungstate.

8. The method according to any one of the preceding claims, characterized in that fibers of the fiber material (102) are made of one or more of the following materials: oxidic ceramic material, in particular aluminum oxide, carbon, silicon carbide, aramid, glass.

9. The method according to any one of the preceding claims, characterized in that the fiber material (102) comprises short fibers or is formed therefrom and in particular comprises fibers with an average length of approximately 2 mm to approximately 40 mm or essentially of fibers with an average length is formed from about 2 mm to about 40 mm.

10. The method according to any one of the preceding claims, characterized in that an orientation of the fibers in the near-net-shape fiber body (100) is predetermined by an envelope of the sieve mold (110), the fibers are in particular oriented essentially along a surface that is parallel to the envelope of the sieve form (110) is arranged.

11. The method according to any one of the preceding claims, characterized in that the near-net-shape fiber body (100) has a fiber content in the Z-direction of at most 7 vol .-%, in particular of at most 3 vol .-% and in particular of at most 1 vol. %, wherein the Z-direction is arranged transversely to a surface along which the fibers in the near-net-shape fiber body (100) are essentially oriented.

12. The method according to any one of the preceding claims, characterized

characterized in that the fiber body (100) is formed substantially while maintaining a fiber bundle structure, the fiber bundle structure preferably being retained at 80% or more, in particular 90% or more, of the fiber material (102).

13. The method according to any one of the preceding claims, characterized in that one or more longitudinal center axes of the one or more passage openings (112) of the sieve mold (110) are arranged transversely with respect to radial directions of a longitudinal center axis (145) of the sieve mold (110).

14. The method according to any one of the preceding claims, characterized in that within a container (104) in which the fiber dispersion (108) is received, the sieve mold (110) is subjected to negative pressure by means of a conveyor (124), wherein In particular, incompressible fluid (106) is diverted from the container (104) through a fluid outlet (121) by means of a conduit device (118) and reintroduced into the container (104) by means of a conveying device (124) through a fluid inlet (123).

15. Fiber body (100) which is produced by a method according to one of claims 1 to 14.

16. A method for producing a ceramic component (150),

full :

Production of a near-net-shape fiber body (100) according to one of claims 1 to 14;

Carrying out pyrolysis on the near-net-shape fiber body (100), an open-pore carbon body (140) being produced; and

Carrying out a ceramization on the resulting open-pore carbon body (140).

17. The method according to claim 16, characterized in that the

Ceramization is carried out by infiltrating the open-pore carbon body (140) with a carbide former, the carbide former being in particular silicon.

18. The method according to claim 16, characterized in that the ceramization is carried out by infiltrating the open-pore carbon body (140) with a polymer material, in particular an organometallic or organosilicon polymer material, and subsequent pyrolysis.

19. Ceramic component (150) which is produced by a method according to one of claims 16 to 18.

20. Ceramic component (150) according to claim 19, characterized in that a fiber content is approximately 50% by volume or less, in particular approximately 25% by volume to approximately 35% by volume, based on a total volume of the ceramic component (150 ) is.